Noncontact gap measurement (relative displacement, axial shift), displacement range and amplitude, vector sum (peak value) vibration displacement via two channels, momentary value of vibration displacement, range of vibration displacement at infralow and low frequencies, rotation frequency with registration phase point.

Area of application

It is used to control positions and vibration displacement of structural elements of steam and gas turbines, pumps, engines and other mechanical equipment as constituent part of measuring systems based on IEA RS-485 fieldbus and/or unified electric analogue signals.

Depending on a voltage transducer’s (VT) design (Table 1.1) displacement sensor (DS) DP I (hereinafter DS) may have one or two measuring channels (symbolic notation of the channels – Х и Y). Each channel has a digital output and analogue ones – current and voltage outputs. The DS with voltage transducer 7 has an additional buffered voltage output intended to operate a communication line of up to 300 m length.

While measuring a vector sum’s amplitude of vibration displacement of Х and Y channels, both channel outputs are connected, in this case one may use only analogue outputs for operation.

The DS has a wide range of functional capabilities as well as performs the functions of an axial shift sensor (gap, shift, and displacement measuring), vibration displacement sensor (measuring of amplitude, vibration displacement range or vector sum (for two channels version), presentation of instantaneous values of vibration displacement), and rotation frequency sensor. Each channel of DS can be adjusted for measuring modes specified in Table 1.1. The DS may have different measuring modes via channels.

Each channel is adjusted to the measuring modes having the ranges specified at order. While being manufactured, one of the adjusted modes (specified at order) is setup in each DS channel. The other modes, if necessary, can be setup in the course of operation (via RS-485 interface). Data exchange via RS-485 interface is conducted using a basic protocol MODICON MODBUS RTU in compliance with Modicon Modbus Reference Guide (PI-MBUS-300 Rev.C). If it is necessary to use an exchange protocol that is different from the basic one its special features shall be specified at order.

The DS adjustment and control (setting up of measurement modes and ranges including filters) are implemented via RS-485 interface (via digital output). The DS can be used without digital outputs in this case the previous DS adjustments are saved.

Each DS channel has internal memory (buffer) for recording instantaneous values of vibration displacement. These values can be used for diagnostics of controlled equipment from thebuffer and via voltage outputs. While measuring rotation frequency, the DS with VT 8 and VT 9 controls rotation of a shaft-turning gear (STG) within a period of the gear wheel teeth passing, which equals to 1–13000 ms, setting up a flag/μm in digital code via interface RS- 485 including change of discrete values of the current at STG rotation. There is a possibility of adjustment at operating conditions.

Table 1.1

Measurement modes
Amplitude of vector sumof vibration displacement of X and Y channels
*Only in DS with two channels, moreover contacts 5 and 10; 7 and 8; sockets 6 and 9 of NT shall be connected in pairs. This mode can be setup both via Х channel, and К channel. In the second channel the mode “Amplitude of vibration displacement” is setup automatically.
** Only in DS with NT8, NT9.
*** Only in DS with NT7.

Technical characteristics

Measured gaps range (displacements), max, mm	1,2–2,5
Peak-to-peak value of vibration displacement, max, μm	125–350
Rotation frequency measurement range, r/min	nmin – nmax, where nmin = 60/ Kn r/min, nmax = 2,4·105/Кn r/min, Kn – number of gear wheel teeth, units
Measured passing frequency of gear wheel teeth, Hz	1–4000
Peak-to-peak value of LF vibration displacement, max, μm	400
Basic error limits:
In a displacement measurement mode, (absolute) digital output, μm	± 40
current output, μm	± 50
In a vibration displacement measurement mode	(0,06 + 0,5/Si)·100%, where Si – measured value of vibration displacement, μm
In a rotation frequency measurement mode:
digital output (absolute), r/min;	± 1·10-3·nmax
current output (relative)	± (0,03 +0,02 Imeasure- 4 )·100%, where Imeasure – output current value, mA
In a LF vibration displacement peak-to-peak measurement mode (absolute), μm	± 20
Frequency range (low frequency filter (LFF) is switched off), max, Hz	10–1000
Сut-off frequency of digital LFF, Hz	F1-500, F2-750, F3-1000
Power supply voltage, V	18–36
Consumed power, W, at least for DS with two channels	2,3
for DS with one channel	2,0
Useful current, max, (at supply voltage 18 V), mA, at least for DS with two channels	100
for DS with one channel	75
Mean time to failure, h, at least	50 000
Specified lifetime, years	12

Power-supply circuits have galvanic isolation from output circuits and housing.

Operation conditions

Operation temperature range:
for eddy-current transducer (ECT), оС	-40 ... +150
for normalizing transducer, оС	-40 ... +70
IP Code according to GOST 14254-96:
for NT1 – NT6, NT9	IP54
for NT7 and NT8	IP30
for ECT (without a connector)	IP66

The equipment comprises:

1. Eddy-current transducer according to Table 1.2.
2. Eddy-current transducer (see Section “Harness and eddy-current transducers”).
3. Harness (see Section “Harness and eddy-current transducers”).

Table 1.2

Normalizing transducers

Код	Канал	Explosion protection	Fig. No.
NT1	Х и Y	1Ex[ib]mIIBT6	1.1
NT2	One channel	1Ex[ib]mIIBT6	1.2
NT3	Х и Y	1Ex[ib]mIIBT6	1.3
NT4	One channel	1Ex[ib]mIIBT6	1.4
NT5	Х и Y	-	1.5
NT6	One channel	-	1.6
NT7	One channel	-	1.7
NT8	One channel	-	1.7
NT9	One channel	1Ex[ib]mIIBT6	1.4

Operation details: State Register No. 34132-07. Type Approval Certificate RU.C.27.011.A No. 44488. Certificate of Conformity No. ROSS RU.GBО4.VO1239. It operates at GAZPROM facilities since 2004 (“Compressor complex”, “Zavod “Kirovenergomash”, “Vega-GAZ”), Rostov NPP, Balakovo NPP.